［动词的语态］短语动词的被动语态

短语动词是一个整体，不可丢掉后面的介词或副词。例如：

　　My sister will be taken care of by Grandma. 我妹妹由奶奶照顾。

　　Such a thing has never been heard of before. 这样的事闻所未闻。